Spindle drive assembly

Abstract

To improve the function of a spindle drive assembly.SOLUTION: A spindle drive assembly (10) for opening / closing a flap or the like of an automobile by means of a motor drive includes a spindle unit (20) arranged in a spindle housing (12), the spindle unit including a fixed portion of a spindle drive section having a motor gear unit (18) and a rotating spindle (26) driven by the motor gear unit (18), and a movable portion having a threaded spindle nut (32), the movable portion being axially movable between a contracted position and an expanded position. A first compression spring (44) places the fixed portion and the movable portion of the spindle drive section under tension and assists the movable portion when the movable portion of the spindle drive section moves from the contracted position to the expanded position. A second compression spring (48) is arranged between the movable portion and the fixed portion of the spindle drive section and assists the first compression spring (44) during the opening operation starting from the contracted position of the movable portion of the spindle drive section.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a spindle drive assembly according to the general concept of claim 1. [Background technology]

[0002] To be able to close the doors, flaps or bonnets of motor vehicles in an automatic and controlled manner, it is preferable to use electric drive systems in combination with passive components such as air springs.

[0003] Electric drive systems often consist of a spindle drive assembly and typically include an electric drive system that acts on a flap on a moving vehicle to open and close the flap.

[0004] To allow the length of the spindle drive assembly to be changed, a spindle gripped by a spindle nut is rotated and the spindle is driven by a motor gear unit. The spindle nut itself is rotatably and translatably mounted on a moving part of the spindle drive. The moving part of the spindle drive can move linearly and can be directed towards the stationary part of the spindle drive. As the spindle rotates, the spindle nut, together with the moving part of the spindle drive attached to the spindle nut, moves axially between retracted and extended positions relative to the stationary part of the spindle drive by gripping the threads of the spindle nut.

[0005] The spindle drive assembly is attached at a fixed end to a vehicle and at a movable end to a movable vehicle flap so that linear motion of the spindle drive assembly is translated into opening and closing motion of an associated vehicle flap or vehicle door.

[0006] A spindle drive of the above mentioned type is known from the prior art, as disclosed in DE 10 2017 128 391 A1.

[0007] The known spindle drive assembly has the problem that in the closed position of the car flap, due to the way it is installed, there is only a small angle between the car flap and the spindle drive assembly, thus reducing the available lever. This means that if the initial opening angle of the car flap is small, a high level of motor power is required to initiate the opening movement. During the opening movement, the opening angle becomes larger and therefore the lever also becomes larger, requiring a portion of the initial motor power to continue the opening movement. As a result, a correspondingly more powerful drive motor is required, which requires more space for installation and increases costs. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] DE 10 2017 128 391 A1 Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to improve the functionality of the spindle drive assembly, especially when controlling small opening angles of the flaps. [Means for solving the problem]

[0010] According to the invention, this problem is solved by a spindle drive assembly having the characteristics set forth in claim 1.

[0011] Preferred embodiments and additional advantageous features of the invention are the subject of the subclaims.

[0012] A spindle drive assembly for motor-driven opening and closing of vehicle flaps or the like, comprising a spindle housing in which a motor gear unit and a spindle unit are arranged, the spindle unit being made up of a fixed part of the spindle drive including a rotating spindle driven by the motor gear unit (18) and a movable part of the spindle drive moving axially relative to the fixed part of the spindle drive including a threaded spindle nut gripping the spindle. The movable part of the spindle drive is axially movable between a retracted position and an extended position by a movable spindle nut arranged on the spindle. A first compression spring is envisaged, which places the fixed part of the spindle drive and the movable part of the spindle drive under tension relative to each other to assist the movable part of the spindle drive in moving from the retracted position to the extended position.

[0013] According to the invention, a second compression spring is arranged between the movable part of the spindle drive and the fixed part of the spindle drive, which assists the first compression spring during the opening movement starting from the contracted position of the movable part of the spindle drive.

[0014] Both the first and second compression springs are under tension when the movable part of the spindle drive is in a fully contracted position. During the opening movement of the movable part of the spindle drive, the opening movement is assisted by the spring forces of the two compression springs. The first compression spring assists the entire opening movement, while the second compression spring assists preferably only a certain distance at the beginning of the opening movement.

[0015] When the car flap is closed and the spindle drive assembly is in the retracted position, the angle between the spindle drive assembly and the flap, and thus the lever, is relatively small, so that the spindle drive assembly can transmit only a small force to the flap. In this position, the spring force of the first compression spring is assisted by the second spring, facilitating the opening of the car flap.

[0016] Starting from the retracted position, the second compression spring assists the opening movement of the movable parts of the spindle drive along at least an initial distance. According to a preferred embodiment of the invention, the second compression spring is arranged axially between the spindle bearing attached to the fixed part of the spindle drive and the spindle nut. The fixed part of the spindle drive includes a guide tube in which an axially movable push rod is arranged. The push rod and the spindle nut attached to the push rod are part of the movable part of the spindle drive. The spindle grips the spindle nut and extends inside the push rod. During the opening movement, the second compression spring relaxes and in the relaxed state stops acting on the spindle nut, whereby only the force of the first compression spring continues to act on the movable part of the spindle drive.

[0017] According to a preferred embodiment of the invention, the second compression spring is arranged in a dirt-resistant, waterproof, sealed hollow space bounded by a guide tube, a spindle nut guided in the guide tube, and a seal at the end of the guide tube closest to the spindle.

[0018] The spring constant of the second compression spring may be different from the spring constant of the first compression spring to individually adjust the tension of the initial opening action.

[0019] In particular, the spring constant of the second compression spring may be higher than the spring constant of the first compression spring, resulting in a greater tension in the retracted position of the spindle drive.

[0020] Preferred embodiments of the invention are described in more detail below with the aid of the drawings, from which further features and advantages of the invention are apparent. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a cross-sectional view of the spindle drive assembly in a retracted position. [Diagram 2]FIG. 2 is a cross-sectional view of the spindle drive assembly in an extended position. [Diagram 3] FIG. 2 is an exploded view of the spindle drive assembly. [Figure 4] FIG. 13 is an exploded view of the guide tube and push rod components. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] 1 shows a spindle drive assembly 10, preferably for motor-driven opening and closing of vehicle flaps (not shown) or the like. The spindle drive assembly 10 consists of a spindle housing 12 which extends along a spindle axis 14 and includes a first end piece 16a which may be attached, for example, to the vehicle chassis. A second end piece 16b is connected to the vehicle flap to be controlled. Within the spindle housing 12 is a motor gear unit 18 and a spindle unit 20.

[0023] In the embodiment shown, the motor gear unit 18 is positioned against rotation within the spindle housing 12 by two bearing parts 22a, 22b.

[0024] The spindle unit 20 consists of a guide tube 24 in which a rotatable spindle 26 is disposed. The spindle 26 is positioned at the end of the guide tube facing the motor gear unit 18, preferably using a roller bearing 28.

[0025] In the illustrated embodiment, the guide tube 24 is attached to the spindle housing 12 by a bracket 46, for example by gluing or welding to the spindle housing.

[0026] A push rod 30 is disposed between the guide tube 24 and the spindle 26 and is connected to the spindle 26 by a rotationally and axially fixed spindle nut 32 disposed at the end of the push rod. The spindle nut 32 is preferably made of plastic and the push rod 30 is preferably made of metal. The spindle 26 is rotatable and axially guided at its free end within the push rod 30 by a bearing arrangement 34. The bearing arrangement 34 further acts as an end stop for the spindle nut 32 and limits the axial movement of the spindle nut 32 on the spindle 26 so that the spindle nut 32 cannot move beyond the free end of the spindle 26.

[0027] The motor gear unit 18 comprises a drive motor 36 including a drive shaft 38 which is connected to the spindle 26 by gears 40 (not shown in detail) which cause the spindle 26 to rotate.

[0028] The other end of the push rod 30 is connected via an end piece 16b to a housing tube 42, which is guided in the spindle housing 12. When the spindle 26 is rotated by the motor gear unit 18, the push rod 30 connected to the spindle nut 32 translates along the spindle 26 due to the action of the thread of the spindle nut 32. The push rod 30 and the connected housing tube 42 therefore telescopically move relative to the spindle housing 12 from a contracted position to an extended position. In response, the controlled vehicle flap moves, for example, from a closed position to an open position.

[0029] In the space between the housing tube 42 and the guide tube 24 is a first compression spring 44 to help provide force to the spindle drive 20 during the extension movement of the pushrod 30 and housing tube 42.

[0030] The compression spring 44 surrounds the guide tube 24 and is supported at one end by a bracket 46 for the guide tube 24 and at the other end by the connection between the housing tube 42 and the pushrod 30. The length of the first compression spring 44 is preferably measured so as to provide a force throughout the entire extension movement of the spindle drive. According to the invention, a second compression spring is envisaged, which is arranged in the space between the spindle 26 and the guide tube 24. In the contracted position of the spindle drive, the rear end of the second compression spring 48 is supported at its front side by a bracket 50 which in turn fits into the spindle bearing 28, while the front end of the second compression spring 48 is supported at its front side by the spindle nut 32.

[0031] The second compression spring 48 does not require corrosion protection since it is located in an enclosed area of ​​the spindle drive and is not accessible to water or dirt.

[0032] The second compression spring 48 is used to increase the spring force acting on the moving parts of the spindle drive during the opening operation, thereby reducing the energy consumption and noise generated by the motor gear unit 18. The length of the second compression spring 48 is preferably significantly shorter than the length of the first compression spring 44, so that the auxiliary force is only effective over a limited initial distance during the opening operation.

[0033] 2 shows the spindle drive assembly 10 in an extended position. It can be seen that the pushrod 30 and housing tube 42 are disposed to the left in the extended position relative to the fixed guide tube 24 and spindle housing 12. The first compression spring 44 is also in an extended state.

[0034] The short second compression spring 48 is in a fully extended, relaxed state and is no longer engaged with the spindle nut 32. The spindle nut 32 is already positioned near the free end of the spindle 26 near its final position.

[0035] FIG. 3 shows an exploded view of the basic components of the spindle drive assembly 10 described above, in particular the spindle housing 12 including the end pieces 16a, 16b, the drive motor 36 disposed within the spindle housing 12 including the gear 40, the guide tube 24 including the bracket 46 and the displaceable push rod 30 within the guide tube 24, the first compression spring 44, and the housing tube 42 surrounding the compression spring 44.

[0036] FIG. 4 shows an exploded view of the basic kinematic components, in particular the guide tube 24 including a bracket 46 for mounting to the inner circumference of the spindle housing 12, the push rod 30 disposed within the guide tube 24 including the integral spindle nut 32, a second compression spring 48 fitted to the front face of the spindle nut 32, the bracket 46 for the second compression spring 48, and the spindle 26 gripped by the spindle nut 32, which extends inside the push rod 30 and can rotate within the spindle housing 12 by means of roller bearings 28. [Explanation of symbols]

[0037] 10 Spindle Drive Assembly 12 Spindle housing 14 Spindle axis 16a End piece 16b End piece 18 Motor gear unit 20 Spindle unit 22a Bearing parts 22b Bearing parts 24 Guide tube 26 Spindle 28 Roller bearings 30 Push Stick 32 Spindle nut 34 Bearing configuration 36 Drive motor 38 Motor shaft 40 Gear 42 Housing tube 44 First compression spring 46 Bracket 48 Second compression spring 50 Bracket

Claims

1. A spindle drive assembly (10) for motor-driven opening and closing of a flap or similar in a vehicle includes a spindle housing (12) in which is disposed a motor gear unit (18) and a spindle unit (20) which is axially rotatable relative to a fixed portion of the spindle drive including a rotating spindle (26) driven by the motor gear unit (18) and a threaded spindle nut (32) which grips the spindle (26). a movable part of the spindle drive that moves axially between a contracted position and an extended position by means of the movable spindle nut (32) arranged on the spindle (26); a first compression spring (44) is envisaged, which places the fixed part of the spindle drive and the movable part of the spindle drive under tension relative to each other and assists the movable part of the spindle drive when it moves from the contracted position to the extended position; a second compression spring (48) is disposed between the movable part of the spindle drive and the fixed part of the spindle drive, and assists the first compression spring (44) during an opening movement starting from the contracted position of the movable part of the spindle drive. Spindle drive assembly.

2. 2. The spindle drive assembly of claim 1, wherein the second compression spring (48) supports the movable portion of the spindle drive along at least an initial distance beginning from its retracted position.

3. 3. The spindle drive assembly of claim 1 or 2, wherein the second compression spring (48) is axially disposed between the spindle nut (32) and a spindle bearing (28) attached to a fixed part of the spindle and disposed within a push rod (30).

4. 4. The spindle drive assembly of claim 1, wherein the second compression spring (48) is disposed within a hollow space that is sealed, dirt-resistant and waterproof.

5. The spindle drive assembly of any one of claims 1 to 4, wherein the second compression spring (48) has a spring constant different from the spring constant of the first compression spring (44).

6. The spindle drive assembly of any one of claims 1 to 5, wherein the second compression spring (48) has a higher spring constant than the first compression spring (44).

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